The stereo in my 2012 TRD Sport 4x4, not the JBL or Nav unit, but the standard one I guess you would call it, is pretty decent sounding. I did miss having just a little bass as I have had systems in my last 2 F250's over the last 8 years.
Did a lot of reading here and decided to keep it pretty much stock and simple. I choose to install a Sound Ordnance B-8pt, especially since Crutchfield has it for $199 plus a free power installation kit. I also had a $20 credit there, so I spent $179 w/free shipping.
The installation of the 2012 4 door is pretty easy. Thru the firewall there is a separate rubberized grommet beside the main wire entrance. There is a small cable going thru the hole and just enough room to add the power cable. Then, easily ran to the driver side rear seat under sill plates. The amp/sub fits nicely in the bin behind the rear seat. Did drill one hole thru the plastic to run all wires into the cubby hole. I lined the cubby hole with trunk liner to make sure there are no rattles and used a little adjustable strap to hold the speaker in place. I ran the 2 sets of speaker wires and amp blue wire up the passenger side.
The rear speaker wires are in their own plug in the rear of the factory head and easy enough to splice into. I soldered all 4 to make sure I had the best connection possible. The blue wire is spliced and soldered into the gray wire.
That is all there is to it. The SO gives a nice addition to the bass without being over powering and entertaining your neighbors. I would rate the amp/sub unit an 8.5 out of 10 and installation something a novice (as my self) can do.